Dkk-piate reciieier



July 28, 1953 w. M. LACEY 2,647,227 DRY-PLATE RECTIFIER Filed Jan. 28, 1949 Fig. 2

JNVENTOR. Mllacey Alto/hey Patented july 28, 1,9513

DRYAPLATE enormen.

Wiliam Lacey; Medford, Mass., assigner to Sylvania Electric- ProductsA Inca, a corporation of Massachusetts pplicationJanuary 28, 1949, Serial No. 73,246 I4 Claims; (Cl. 317-241)` The present invention relates to dry-plater'ectiers, and is concerned especially with the physical arrangement of the parts for excellent per# formano@ characteristics While affording economy in` manufacture, and saving of space When wired into circuit applications.

Dry-plate rectifiers have heretofore been used widely and certain characteristics have come to be recognized as essential to satisfactory operation. In selenium rectiers particularly, the free and extensive exposure4 of therectifier plates to cooling air or the like is needed toA dissipate the destructive heat generated in the rectier. A single rectier plate comprisingI` a`4 carrier eiecjtrode, a layer of carefully processed-selenium, yandv a counter' electrode on the selenium, with anelec'- troformed barrier layer between the Acounter elec-- trode and the selenium', can withstandV a backvoltage of the order of 3'0- volts' and willpass our`A rent' in a forward drectionsubstantially inproportion to the area of the plate.

In order to withstand high back-Voltage; selenium rectier plates have commonly heen stacked, with washers separating the plateseto 4providel space for ventilation sov that tlre counter electrodev of one plate isv connectedby a washer'- to the carrier of the next.

In accordance with the present inventionanew arrangement of plates is provided that eliminates many of the parts required in prior-artseries connected rectiner assemblies and provides more effective cooling that reducesthe operatingterrrperature and improves rectification efficiency. In practising theV present invention, rectifier plates are arranged in successive overlapping'V relation, with gripping means arranged laterally along the series-connected overlapping plates. The accompanying drawings show several illus trati-ve forms of the invention, which are described in detail in the following description of the illustrated embodiments. From these, variousl features of the invention will be understood and readily appreciated.

In the accompanying" drawings-z Fig; l is an enlarged sectional view of apa-irof plates arranged in overlapping relation lin accordance with the present invention:

Figs. 2 and 4 are front and end elevations, re-

spectively, of a four-plate rectierin aocoI-'cl'a'nce4 with the present invention;

Fig. 3 is a cross-sectonal'view along Ythe` line 33 of the rectifier in Fig. 2; and

Figs. 5` and 6l are cross-sectional. views of other forms of dry-plate rectiiiers, theSegUresBeng' comparable to' Fig. 3.

)In Fig. I a pair of rectifier plates t0, lare shown connected in series, the rectifier plates' themselves constituting al1 of the required elec-v trical circuit except for the terminals. Each plate includes a carrier electrode I'4, I4', a layer of selenium t6 or i6" processedin accordance with known techniques, and a counterelectro'de' i8 or l8r. A'loarrierv layer is believed to be formed electrically between counter'electrode lil' andl semiconductor electrode f6. The barrier layer andthe selenium constitute a rectifying' layer.v Counter-v el'ect'r'ode I`8`, lil is usually terminated short of the edges of the plate so as to avoid short-circuits across layer IG, f5'. The contact'between theex` posed surface of counterelec'trode I8 and' the opposite surface of' carrier electrode M" directly provides a series connection between two rectiner plates so as to Venalo'le the two plates to withstand a voltage applied between plate li'andfcounterelectrode H3" that is equal to substantially double that of a' single rectifier' plate. The current passed by theentire area ofV the selenium is con-` ducted inthe plane of the counterele'ctrode to the carrier electrode'of the next contacting plate. ,o In the region where the two plates are over' lapped', incre heat is developed than elsewhere du'e to. the passage of' currentthrough two sele'ni-f um layers'. Were the temperature allowed to' rise` excessively, the rectifying, properties of the plates.

would degenerate, and thev plates might deteriorate permanently. But. because thecarrier electrode s formed of a good heat conductor such= as overlap regions is distributed to areas of the plates that are exposed for eiicient dissipation.

The overlap areaY should vbe restricted. to a. relatively smallfraction ofthe totalplate area for most effective ventilation.

In' Figs; 2to- 4 inclusive a rectifier is shown enibodying' the edge-overlap arrangement in Fig. 'lifhe4 entire` assembly provides a mechanical conv that the assembly iscapalolev ofY withstanding approximately four times the backvoltage that. one wijn withstand: electrode is'represented by the stippledsurface,l and by rough lines in. the cross-sectional views.) By restricting the extent fraction of' the plate area, the heat-dissipation of (In these guresf the counter` the plate is found to be at least equal to a stack of plates secured together mechanically but spaced apart by conductive washers` connecting each plate to the next in series.

Along the lateral edge of the series of plates a mechanical clamp is provided, the lateral edge being that which crosses the overlapped edges. In the form of rectier in Figs. 2 to 4, .a metal channel 28 is provided, clamping each plate against the next. Metal channel 28 is insulated from all of the plates by a layer 30 of impregnated paper or other suitable insulating material. This paper extends over one face of plates 23 to 26 to insure insulation from a metal chassis in the event that the rectifier is mounted close to the chassis in its circuit application. In the areas not enclosed by channels, the paper should be perforated liberally to promote cooling of the plates. For securing the rectier as a unit to the chassis in which it is to` be used, lugs 32 are provided, struck out of channel 28. These lugs can be projected through holes in the chassis and the projecting lug portions then are to be bent or twisted to hold the rectiiier iirmly in place.

Channel 28 resiliently enforces contact between plates and 22 in their overlap region, at least along the bottom or lateral edge, and likewise insures mechanical and electrical connection be-` tween plates 20 and 22, between plates 22 and 254, and between plates 24 and 26. Metal terminals 34 and 36 are also pressed by channel 28 and the intervening paper insulator 3!! against plates 2li and 26 respectively, the thickness of terminals Sli and 36 being appropriate to a tight t.

The entire assembly is mechanically and electrically sta-ble and it affords extensive coolingsurface for efficient operation and long life. The'assembly as illustrated is normally coated by dipping into insulating waterproofing paint for protecting the plates against atmospheric moisture and this further promotes mechanical stability. Aside from the plates themselves and the necessary terminal strips to which circuit connection is made, it is notable that only the single insulated channel 28 is required.

In order to assemble this strip rectier the four plates are held loosely in desired overlapping relation and against insulating sheet 36 that is folded over one edge of the plates; and channel 28 is then forced across the lateral edges of the plates.

The overlap and the direct-contact between the plates are features of the rectifier in Figs. 2 to 4, and of the other forms of plate rectiiier in Figs. 4 and 5. In Fig. 4 metal channel 28', provided with mounting lug 32 and insulating sheet 30 grips a series of six plates 20', 2l, 22', 23, 24 and 25, the plates being inclined in relation to the channel. Plates 2l and 22 are in limited overlapping edge contact and plates 23 and 24 are similarly held in overlapping edge contact. Pairs of plates 20 and 2|, 22' and 23, and 24 and 25 are shown in full overlapping relationship, an arrangement which somewhat reduces the currenthandling capacity of the plates per unit of area but which greatly increases the back-voltage rating without correspondingly increasing the overall length of the strip-rectifier. The sloping arrangement of plates is mechanically stable, being sustained at the ends by appropriate forming of terminals 34 and 36', sheet 30 being doubled at' a for more iirmly securing terminal 34 in its place in the assembly.

In Fig. 6 another edge-overlap arrangement of rectifier plates is shown having the merit in common with the form of Fig. 2 of eiiicient heat-dissipation due to large and eiectively exposed surfaces of the rectifier plates; and the further merit of direct connection between each plate and the next without increase in the number of parts required, such as where a separate connector from each plate to the next is required. In the form of plate-rectifier in Fig. 6 the sloping relationship of the plates with lrespect to the paper insulation is avoided. In order to achieve this result, however, a portion of plate 26 opposite bracket 26a is required to be bare of semi-conductor and counterelectrode, this arrangement being characteristic of the other plates 20", 22 and 24 as well. The arrangement in Fig. 6 is of excellent mechanical stability, and avoids concentration of stress by the squared edges of the plates against the insulation. However it requires larger carrier electrodes and occupies a greater overall length than the forms of rectier in Figs. 2 to 4.

Various other rectifiers embodying various features of the foregoing rectifiers, having plates connected in series and arranged in a strip, will occur to those skilled in the art; and for this reason the appended claims should be allowed such broad interpretation as is commensurate with the spirit and scope of the invention.

What is claimed is:

l. A dry-plate rectier comprising multiple plates each having a counterelectrode, a carrier electrode, and an intervening rectifying layer, said plates being series-connected with the counterelectrode of one plate overlapping the carrier electrode of the next plate repeatedly in sequence, the area of overlap of each contact being restricted to a small fraction of the total rectifying area of any of the plates.

2. A dry-plate rectifier comprising a series of rectangular plates each having a sheet-metal carrier electrode, a counterelectrode, and a rectifying layer interposed between said electrodes, said plates being arranged in a strip `and including one plate having only a small portion of its counterelectrode at one edge in contact with the carrier electrode of one adjoining rectifier plate and having only a small portion of its carrier electrode at the opposite edge in contact with the counterelectrode of another adjoining rectifier plate.

3. A dry-plate rectier comprising a series of substantially flat rectangular plates each havinga sheet-metal carrier electrode, a counterelectrode substantially coextensive with said carrier electrode, and an interposed rectifying layer, said plates being connected in series with the rear surface of each plate in physical contact with the front surface of the next, the area of each contact being limited to less than half of the area of any one plate.

4. A dry-plate rectifier comprising multiple plates each having a sheet-metal carrier electrode, a counterelectrode virtually coextensive With said carrier electrode, and an intervening rectifying layer, said plates being series-connected in overlapping edge relationship, the overlapping edges being gripped together at one end thereof by an insulating channel extending across all said plates.

5. A dry-plate rectiiier comprising multiple rectangular plates each having a sheet-metal carrier electrode, a counterelectrode, and an intervening rectifying layer, said plates being connected in series and arranged in sequence with opposite ends in overlapping contact, the contact area being limited to a small part of the total rectifying area of each plate, and the lateral edges of all the plates being gripped to maintain the overlapping contact by an insulated channel.

6. A dry-plate rectifier comprising multiple rectangular''plates each having a substantially flat sheet-metal carrier electrode, a counterelectrode, andl n interposed rectifying layer, said ries of plates;A a parallel-Walled gripping device along an eclg'ev of the series of plates to maintain g contact, and terminal connecetween each of the end plates of said parallel-walled device,

ctier comprising a. series of recving a sheet-metal carrier elec-v trode, a cojinterelectrode, and an interveningI rectifying layer, said plates being arranged in series electrically and mechanically, with op-gA posite edgesfof all but the end plates of the se-"L ries in overlapping relation, the extent of overlap being limited to a minor part of the rectifying area ofj'each plate, and a gripping device in engagementy'with the series of plates along one.

edge therecf, said rectier being coated with*l a mechanically stabilizing waterproofing coating.

8. A rectifier according to claim 1 wherein the .rectifying layer is largely selenium.

,'9. A rectifier according to claim 2 wherein the rectifying layer is largely selenium.

10. A rectier according to claim 3 wherein the lrectifying layer is largely selenium.

11. A rectifier according to claim 4 wherein the rectifying layer is largely selenium.

12. A rectifier according to claim 5 wherein the -q'rectifying layer is largely selenium.

13. A rectifier according to claim 6 wherein the rectifying layer is largely selenium. 14. A rectifier according to claim 7 wherein the rectifying layer is largely selenium.

WILLIAM M. LACEY.

References Cited in the le of this patent UNITED STATES PATENTS 

